Slug for cleaning condenser tubes



Nov. 8, 1%32.

w. F. OBERHUBER 1,886,419

SLUG FOR CLEANING CONDENSER TUBES Filed Feb. 9, 1929 Patented Nov. 8, 1932 v ummmre entree winmarr oiinnnuenn, on LAnsnoWnn, PENNSYLVANIA, Assrenoa T0 FRANKLIN nEvnLorMnnr Comment, or PHILADELPHIA, rnnnsytvenre, a CORPORATION or PENNSYLVANIA s Ue roe CLEANING: counnnsne TUBES Application filed. February 9; 1929: Serial No. 338,675

My invention relatestocomposite slugs for usein cleaning condenser tubes andthe like and is of moreparticular reference to the type of slug having a rubber body hollow for a considerable portion of its length from'lts rearward end and having a metal scraper at its forward end, the driving fluid for slugs of this type beingusually water.

A purpose of my mvention is to provide a composite slug of the character indlcated 'adaptedto easy and inexpensive manufacture and well suited. to the needs of service.

A -further purpose is to combine a more greatly reduce longitudinal compression stresses in thematerial of'the body along the portion thereof engaging the tube.

Further purposes will appear inthe specification and in the claims. i z 7 I have elected to illustrate myinvention by one-main form onlyishowing however a a p rations 17 into the successive flutes at thelr rearward ends from the hollow interior of the body., I

detail modification and selecting a main form and detail modification that ispractlcal and efficient in operation and which Well illustrates the principles involved. 7

Figurel-is a longitudinal view of'a slug embodying my invention inside a condenser tuba-the condenser tube bein'gshown in section and fragment only.

Figure 2' is a front elevation of the slug shown in Figure 1 without the spring piston at its forward end.

e0 the line f .Figure 4.

Figure 6 is a longitudinal side view of .a slug hav ng a rubber body generally similar to that of Figure 1 but having a different form: ofmetal scraper andpiston atits forward end. p

Figure 7 is a left endelevation of Figure 6. Figure 8 is alright end elevation of Fig- Like numerals refer to like parts in all figures. i

Describing in illustration and not vin limitation and referring to the drawing The illustrated embodiment of my invention comprises a composite slug made up of .a rubber body 10, hollow for a considerable portionof itslength at 11 from its rearward end and carrying a spring metal piston upon a forwardly directed nose 12. p a

In the preferred embodiment of my invention the rubber body presents a uniformly end and adjacent and forwardly of the uni formly circular portion' 13 has a cylindrical portion 14 that is longitudinally fluted.

In the fluted portion of the body arcuate surfaces 15 have thesame radius as and are a continuation of the surface 13 and alternate withthe longitudinal fiutes16 which extend .to the forward end ofthemain portion of the slug" 4 The slug is provided with a series of perfothe body of the slug.

The entrance portion of the hollow is preferably provided with a rearward flare at 19, whichmay be omitted however if desired.

The rearward cylindrical portion 13 presents cleaning edgesQO at the rear ends of the flutes against the inside of the tube 21 and other cleaning edges at '22 at the front ends'of the arcuate surfaces 15 intermediate i the flutes.

" In the form shown in Figures 1 to, 5 the forward nose 12 of the body carries a scraper piston 24 that comprises a spiral spring.

The successive turns of the spring rearwardly diverge from the compressed surface 25 of the nose tothe full diameter of thetube and spring press together thus forming a fairly tight piston carried on the nose and adequately sealing the space between the nose and the inside of the tube, the piston in operation tending to pull the main body of the rubber slug forward by thenose, when, as is usually the case, the more forward piscylindrical surface on its outside at 13 -forv 'wardly for some distance from its rearward ton portion of the composite slug tends to travel more rapidly through the tube than the more rearward rubber portion thereof.

The front portion of the rubber slug comprises step sections progressively smaller toward the front, the forwardmost and smallest portion 25 being used when mounting the piston to pull the next section 12 into the central perforation of the piston which compresses the rubber somewhat as best seen in Figure 4 at 25.

The spring piston of Figures 1 and l is thus removably but strongly fastened to the slug by the circumferential compression of the forward turns of the spring into the rubber nose at 25. i V I Whena slug is driving through a tube the forces acting upon it cpmprise'driving forces active across the area of the tube to force the slug along through the tube and resisting forces acting along the circumferential surface or surfaces of the slug that engages or engage the inside of the tube.

In the hollow slug shown in Figure at, the interior area at 19 is approximately one half that'across the whole tube in which the slug is travelling and as a result the longitudinal compression in the portion of the plug that is rearward of this diameter is diminished by the hollow by an amount that is equal to the force that is applied ahead of this diameter, and the perforations 17 which admit the fluid pressure to the space outside and ahead of the main portion of the rubber body additionally reduce this longitudinal compression and also the force of outward expansion of the body against the inside of the tube.

In the slug shown in Figures 6, to 8, the rubber body portion is the same as in the form already described shown in Figures 1 to 5 inclusive, except that any outward perforations from the interior of the plug are not shown in. Figures 6 to 8.

Instead of the spring scraper piston made of a spiral spring I use in the form of Figures 6 to 8 a scraper member 26 and a piston member 25.

The scraper member 26 is desirably. made by die pressing a metal washer and comprises a short cylindrical neck 27 of diameter to tightly fit around the nose of the slug and radially slit rearwardly flaring petticoat members 28.

The outer ends of the petticoat members engage the inside of the tube, thus comprising scrapers.

Immediately outward from the hub of the petticoated scrapers I mount the disc washer member v25 which is in effect a piston.

This member is desirably a spring steel washer having an inside diameter such as to circumferentially compress the rubber nose 12 about as indicated at 25 in Figure 6.

The form of Figures 6 to 8 has the advantage of providing the additional scrapers which obviously however may be omitted if desired.

I prefer the form in which the piston comprises a spiral spring having successive turns pressing together and the outer turns of diameter to resiliently engage the inside of the tube and the inner turns of diameter to compress into the nose of the slug.

In operation the slugs are inserted into the open ends of condenser tubes and water pressure is then sent into'the; tube. back of each slug to drive the slug through the tube, the spring piston presenting its outer circumference against the inside of the tube to scrape off the major portion of the deposit and the cleaning surfaces at 20 and 22 presented by the rubber body giving a wiping action whicheffectively cooperates with the initial scraping by the piston.

The tendency for the rubber body to be expanded by the driving fluid so as to tightly press out against the inside of the tube is very greatly lessened by the passage of the driving fluid through the perforations to the outside of the slug and the fluid that thus passes the perforations engages the rear side of the piston pushing the piston forward which in turn exerts a forward pull upon the nose of the slug upon which it is mounted.

In view of my invention and disclosure .va-

riations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to

obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such in so far as they fall within the reasonable spirit and scope of my claims.

Having thus described my invention, What I' claim as new and desire to secure by Letters Patent is:

1. A composite slug having a hollow interior open at its rearward end and extend- "ing for a considerable portion of the'length of the bodyand having a cylindrical surface for a portion of its length from its rearward end and a fluted cylindrical surfaceforward from the first cylindrical surface, the flutes being spaced circumferentially around the slug, the slug having passages into the flutes from the hollow interior and a piston scraper mounted upona forwardly directed nose of the body. I

2. A composite slug for cleaning tubes comprising a rubber body hollow from its rearward end for a considerable portion of its length and on said length presenting cleaning edges upon its outside surface and apertured from a point in front of some of these cleaning edges into the hollow of the body,

the body having a forwardly directed rubber nose forming a mount for a scaper and a scraper mounted upon the nose and closmg a major portion of the space between the nose and the inside of the tube, the apertures pass ing fluid between the space immediately back of the scraper and the rear of the slug.

3. A composite slug comprising a rubber body hollow from its rear end for a considerable portion of its length, a forwardly directed nose on the body and a spiral spring having inner turns compressing the nose and outer turns against one another flaringrearwardly to engagement with the inside of a tube, the body having a passage from the rearward end of the slug to the space outside the body and immediately back of the spring.

WILLIAM F. OBERHUBER. 

